Abstract
An account is given of my development of techniques to obtain well-spread Giemsa-stained banded chromosome preparations. Apparent G-banding could be obtained following very slight trypsin treatment of freshly prepared slides, but this banding was very fine (close-grained) and possibly not a reflection of chromosome structure. However, treatment of developing embryos in vitro with 5-fluorouridine produced a similar chromomere banding, which is therefore regarded as genuine. Steady accumulation of Helophorus Fabricius, 1775 karyotypes has resulted in the production of an Atlas covering 62 of the 170 species known to occur in the Palaearctic. Chromosome polymorphisms involving pericentric inversions and addition of extra C-banding regions have been found, as well as small B-chromosomes in a few species. In general, karyotypes have proved very useful in establishing the limits of individual species. Parthenogenesis involving triploidy has been found in two species. Karyotypes of experimentally produced hybrids have revealed irregularities in chromosome condensation.
Subject
Genetics,Biotechnology,Animal Science and Zoology,Plant Science
Reference38 articles.
1. A revision of the beetles of the Genus Helophorus F. (Coleoptera: Hydrophilidae) subgenera Orpheloporus d’Orchymont, Gephelophorus Sharp and Meghelophorus Kuwert.;Angus;Acta Zoologica Fennica,1970a
2. Revisional studies on East Palaearctic and some Nearctic species of Helophorus F. (Coleoptera: Hydrophilidae). Ergebnisse der Zoologischen Forschungen von Dr. Z. Kaszab in der Mongolei (No. 226).;Angus;Acta Zoologica Academiae Scientarum Hugaricae,1970b
3. HELOPHORUS ORIENTALIS (COLEOPTERA: HYDROPHILIDAE), A PARTHENOGENETIC WATER BEETLE FROM SIBERIA AND NORTH AMERICA, AND A BRITISH PLEISTOCENE FOSSIL
4. Separation of two species standing as Helophorus aquaticus (L.) (Coleoptera, Hydrophilidae) by banded chromosome analysis
5. Separation of Helophorus grandis, maritimus and occidentalis sp.n. (Coleoptera, Hydrophilidae) by banded chromosome analysis